The separation of racemic mixtures into optical antipodes (enantiomers) represents a very important problem of preparative chemistry. In addition to the conventional methods of converting the racemic mixture into a mixture of diastereoisomers and separating them on the basis of different physical properties, interest has centered in recent years in the main on chromatographic methods for separating racemic mixtures, using in particular optically active adsorbents as the stationary phase.
The problem in particular is finding optically active adsorbents which permit the separation of a large number of chemically different racemates and hence are universally applicable.
It is known for example to polymerize optically active acrylamides and methacrylamides in the presence of a cross-linking agent in suspension, to let these cross linked polyamides swell in appropriate eluents and to use them for separating enantiomers (described in DEP 2,500,523). However, it is highly disadvantageous that these materials are only usable for low pressure liquid chromatography. Under pressures of greater than 5 bar, these crosslinked polyamides are compressed and become impermeable to the eluent, so that the rate of migration decreases significantly. Furthermore, their degree of swelling is dependent on the composition of the eluent. High pressure liquid chromatography of gradient solution is not possible on these gels.